The $18^{th}$ century's Industrial Revolution brought about influx of commerce, industry, and agricultural population into the urban areas, entering the $19^{th}$ century. Quality of rural communities declined, and the exploding population in the cities gave rise to various problems. 'Mietskaserne' Blockhousing was constructed by the 'Hobrechtplan', but led to social problems such as poor living conditions, insufficient sunshine due to overcrowding, slums due to incomplete urban infrastructure, epidemics, and so on. Starting in the early $20^{th}$ century, Berlin has driven forward a remodeling plan under the motto of 'critical reconstruction (kritische Rekonstruktion)'. It is performed in the place, which represents the vicissitudinous history of Berlin with site plans coexisting past with presence, using modern vocabulary of architectural forms. Reconstructing a city is a process which not only raises the economic value of each building consisting a city, but also a redevelopment process that brings out cultural value of an era. When a new era emerges buildings get reconstructed or rebuilt, and thereby form the identity of a city by reflecting its society, culture, politics, economy, and history. Old German architecture were not destroyed or rebuilt recklessly just by the fact that they are functionally or aesthetically outdated. Each building is treated as precious cultural heritage reflecting the history. This is how Berlin is being transformed today.